Can implantation bleeding occur anytime?

Alrighty...i had unprotected on the 19th...and with a condom on the 27th. i started having light spotting that has fit the description of implantation bleeding on the 29th, and tenderness and cramps and fatigue and all that prengnacy greatness. But when i counted days of when i should ovulate thats right at the time i was spotting. The first day of my last period was the 14th and i'm due to start on the 12th or so. Is it possible to have implantation bleeding during ovulation? I thought they could have just been ovulation symptoms but i still have cramps and my are still sore??